Transition-Metal Complexes of a Bifunctional Tetradentate Gallium Alkoxide Ligand

The mixed gallium transition-metal complexes [FeCl{Ga2(tBu)4(neol)2}] (1) and [M{Ga2(tBu)4(neol)2}], M = Co (2),
Ni (3), Cu (4), have been prepared by the reaction of [Ga2(tBu)4(neol-H)2] (neol-H2 = 2,2-dimethyl-propane-1,3-diol) with the appropriate metal halide and Proton Sponge. Compounds 1−4 have been characterized by NMR (3),
UV/vis, and IR spectroscopy and magnetic susceptibility (solution and solid state), and their molecular structures
have been confirmed by X-ray crystallography. The molecular structure of compounds 1−4 consists of a tetracyclic
core formed from two four-membered and two six-membered rings. The central metal atom adopts a square pyramidal
(1) or square planar (2−4) geometry. The magnetic susceptibilities for 1, 2, and 4 are as expected for strong ligand
field environments. On the basis of spectroscopic and structural data, the [Ga2(tBu)4(neol)2]2- ligand appears to be
more flexible than other chelating ligands; this is proposed to be due to the flexibility in the O−Ga−O bond angle.